Title

Influence of cavity size on the response of cavity chambers to 25- and 45-MeV neutrons

Document Type

Article

Publication Date

1-1-1997

Abstract

We calculated the response of gas-cavity dosimeters to 25- and 45-MeV neutrons in order to estimate the portion of the response that originates from neutron interactions within the gas cavity. This affords insight into the validity of the Bragg-Gray theory for dosimeters with finite cavities and also provides a basis for modifying gas-to-wall absorbed dose conversion factors deduced from the Bragg-Gray theory for use with small-cavity dosimeters. For a typical ionization chamber, e.g., with a 1-cm3 propane- based tissue-equivalent gas at standard temperature and pressure, the fraction of the total absorbed dose to the gas cavity from neutron interactions within the gas is 0.09% at 25-MeV and 0.006% at 45-MeV neutron energies. For microdosimetric detectors, the neutron interactions within the gas are negligible above 25 MeV.

Publication Source (Journal or Book title)

Medical Physics

First Page

527

Last Page

533

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